Controlling flow rates



Aug. 18, 1959 l.. .1.l KIRBY CONTROLLING FLOW RATES Filed March 9, 19543 Sheets-Sheet l INVENTOR. nf/rencej/-y Aug. 18, 1959 L. J. KIRBY2,899,969

CONTROLLING FLOW RATES Filed March 9, 1954 3 Sheets-Sheetl 5 I NV ENTOR. aw/@276e /e/'r CONTROLLING FLOW RATES e Lawrence J. Kirby, PortArthur, Tex., assignor to Gulf ,Oil Corporation, Pittsburgh, Pa.,` acorporation of Pennsylvania Application March 9, 1954, Serial No.415,033 claims. (cl. 137-s) This invention relates to a method of -andmeans for controlling ow rates, and, 'more particularly, to a method ofand means for controlling weight rate of ow of liquids.

Conventional means for controlling rate of ilow of liquids havegenerally been based upon volume rate of ow and have proved satisfactoryin cases where the liquid itself presents no particular problem of flowand accurate determinations need not be made. Volume rate of ow,however, is not always very satisfactory in cases where a variation indensity, viscosity and/ or temperature of the liquid is a problem or thequantities of liquid being measured are small. True weight rate of flowhas been accomplished for materials, such as dry solids, through suchexpedients as mechanism involving conveyor means passing over a weighingdevice, but such means are generally not applicable to fluids.

The method of and means for controlling the rate of ow of liquids inaccordance with my invention is characterized by the fact that the rateof ilow of liquid from a receptacle or container is automaticallycontrolled to obtain a predetermined weight rate of oW therefrom. Morespecically, the weight rate of ow of liquid from a receptacle containinga selected amount of said liquid is continuously controlled'bycontinuously measuring the hydrostatic head of said liquid in saidreceptacle, employing an actuating fluid under pressure to control theflow of said liquid from said receptacle, and continuously varying thepressure of said actuating fluid in accordance with changes in saidhydrostatic head. While my invention is applicable in controlling theweight rate of ow of a selected amount of liquid from a singlereceptacle or simultaneously from a plurality of such receptacles, afterwhich the receptacle or receptacles are again filled with aselectedamount of liquid and. the operation vcan again be started, I prefer todischarge one receptacle of substantially its entire liquid contents andsubstantially immediately thereafter switch to another receptaclecontaining a selected amount of liquid. In'this way the operation can bemade substantially continuous.V

The hydrostatic head of the liquid in the receptacle is continuouslymeasured throughout the liquid discharging operations in any convenientmanner. embodiment of my invention, l employ a mercury U-tubedifferential pressure measuring device.

VThe liquid is removed from the receptacle through a liquid dischargeline either by gravity flow or by positive means, such as pump means.Means, such as a control valve, is employed yto control the flow ofliquid from the receptacle through the liquid discharge line. In theevent circumstances permit the use of gravity flow in Vremovinga'selected amount of liquid from the receptacle, the control'valve canbe located in the lliquid discharge line;

supplying power to the pump, the pump suction line` or the pumpdischarge line. In addition, the control valve could also be located ina bypass line joining the pump discharge and suction line or in alinevfrom the.

In the preferred pump discharge line to the receptacle. In each of thetwo latter cases, the pump may be operated at con#A stant speed and thecontrol valve would allow, any' liquid in excess of the desired quantityto ow back to the pump suction line or the line from the pump discharge"line to the receptacle, respectively.

The lcontrol means identified above, regardless of its.

location, is actuated by a'fluid, such as air, under pressure, whichpressure is varied in accordance with changes in the hydrostatic head ofthe liquid in the receptacle. More specifically, the changes inhydrostatic head of the' liquid in the receptacle, as determined, forexample, by a manometer, are transmitted to a pressure indicator,

such as a pressure indicating arm, and the latter, in turn, isassociated with the actuating iliuid in such manner as to' continuouslyvary the pressure of the actuating uid in response to changes in thehydrostatic head of the liquid.

Still more specific and in accordance with an especially preferredembodiment of my invention, an index arm is employed in combination withthe pressure indicator, and. means, preferably cam means, is provided tomove saidY index arm in accordance with the desired weight rate of flowof liquid from the receptacle. As previously noted, the pressureindicator, preferablyin the form cfa pressure indicating arm, is movedin response to the change' in hydrostatic head of the liquid in thereceptacle. This latter movement, as well as that resulting frommovement of the index arm, is then transmitted to the fluid actuatingmeans, with the result that the pressure of the actuating fluidiscontinuously varied.

The invention can best be describedwith reference t0.Lv

liquid contents and a typical hydrostatic headmeasu'ring meansassociated therewith.' Figure 3 is a 'sectional repre? sentation and, inpart, a schematic diagram of'a typical fluid control means used incontrolling the discharge of liquid from the receptacles. Figure 4 is aside view taken in the direction of line IV-IV in Figure 3. is anenlarged sectional representation of a typical flow control valve thatcan be 'used in accordance with my:

invention to control lthe llow of liquid in the discharge line from thereceptacles or flowy tanks.

Referring to Figure 1, reference numeral 2 illustratesV acylindricalreceptacle or tank wherein liquid 4 is stored for subsequent use inaccordance with my invention. In

. order to fill either of charge tanks 6 and 8, or both, liquid isremoved from tank 2 through discharge line 10 containing valve 12 andpumped to the charge tanks through lineV 14 by pump 16. In order to owliquid from line 14 into charge tanks 6 and 8, line 14 is provided withlines 18 and 20 containing valves 22 and 24, respectively.

Pump 16 is operated by steam introduced therein through ly, and line 40.The hydrostatic head readings obtained.v

through means of manometer 30 are transmitted by means 42 to instrument44 which controls the amount of air pressure inline 46 and on controlvalve 43.v In the instant embodiment of my invention, the amount ofpressure oncontrol valve 48 determines the amount of steam which will besupplied through steam line 50 to pump 52. The =latter pump, located online 54, removes liquid A `from tank 6 through line 56 containing valve58 and/or tank 8. through, line 60 containing valve 62.,y Iherwate 9iPatented Aug. 1.8,

Figure 5 flow of liquid from pump 52 is governed by the amount of steamsupplied thereto by line 50. Line 50 preferably contains a hand valve 51interposed between control valve 48and pump 52, which is open suicientlyto permit the free flow of steam to the pump during operation of myinvention. The liquid which is removed from the charge tanks by pump 52is then discharged through line 64 to` any desired point.

vIn order to illustrate an especially preferredembodiment of myinvention, reference should be had to Figures 2 to 5 which illustrate anembodiment permitting continuous liquid flow operations. Charge tanks 66and 68, filled with liquid to any predetermined level by any suitablemeans, for example as shown in Figure l, and from which liquid is to bedischarged, are provided with discharge lines 70 and 72 having valves 74and 76,'respectively, 'located therein and a manometer 78 capable ofcontinuously measuring the hydrostatic head of the liquid in either orboth of tanks 66 and 68. Manometer 78 which is used herein to illustratea preferred'embodiment of my invention, is a float-type mercurymanometer, but

it is understood that other types of manometers or devices capableofmeasuring the hydrostatic head of the liquid in the tanks can also beused in the practice thereof.

Manometer 78 comprises generally a U-shaped tube filled with mercury 80.One side 82 of the manometer, which can be referred to as thelow-pressure side, is enlarged and open to the atmosphere, while theother side means, etc.

116 circumferentially disposed about shaft 108 is an index arm 118provided with a slot 120. Fixedly attached to panel 112 and with aportion thereof spaced sufficiently away therefrom to permit movement ofindex arm 118 and a cam, to be hereinafter described, therebehind, is abar 122 provided with a slot 1247in which rides a roller 126. Roller 126is provided with a shaft 128 which extends through slot 120 of index arm118. Rotatably mounted below barv 122 onshaft 130 is a cam 132 hereinshown provided with a number of iingers134 adaptedf during rotation ofthe cam to engage shaft 128. Cam 132 can be rotated continuously, or atdesired intervals, by any known means such as clock means, electricalPressure indicator 110, index arm 118 and cam 132 are so mounted, asshown in Figure 4, as to move in different planes. Accordingly, nophysical contact exists between these various elements. Also mounted onpanelr112 are switch means 136 adaptedy uponcontact with index arm 118toalternately open and close, through,

electrical circuit means 138, valves 74 and 90 and ,valves 76 and92,respectively. y. j l Associated with pressure indicator 1 10 and indexarm;V

118 is a fluid pressure regulating means for controlling thereof 84,also enlarged and comprising the high-pressure side, is connectedthrough means of line 86 and lines 88 and 89, containing valves 90 and92, respectively, to the base of tanks 66 and 68. In the embodimentshown, the liquid in the charge tanks is lnot permitted direct contactwith the mercury in the manometer, but a solution.94, substantiallyimmiscible and chemically and/or physically neutral to both the liquidin the tanks and the lmercury in the manometer, such as water, methylalcohol, etc., is interposed therebetween and stored in part inreservoirs 96 and 98. This expedient is often desirablein cases wherethe liquid in the tanks can be contaminated by or react with the mercuryin the manometer. While leg 82 of the manometer is shown as being opento the atmosphere, if it is desired to maintain the charge tanks at apressure other than atmospheric, thelow-pressure side 82 of themanometer canV be piped to the space above the liquid in the chargetanks, and theditferential pressure measurement obtained will still beproportional to the hydrostatic head of the Vliquid in the tanks. Y

Resting on the mercury in the high-pressure side of manometer 78 is afloat 100 provided with'a stem 102 at .the upper end thereof. One sideof the stem is prov vided` with teeth 104 in engagement with a gear 106mounted in enlarged portion 84 of the manometer by means of apressure-tight shaft 1'08.

It is obvious in the present embodiment that as the liquid level in thecharge tank and consequently the hydrostatic head thereof varies, thelevel of the mercury Still referring to Figure 3, the hydrostatic heador presi sure of the liquid in the tanks can then be read directly fromcalibrations 114 on the face of panel 112. While I have shown but onespecific means for determiningthe hydrostatic head ofthe liquid in the Vcharge-tanks-and the discharge of liquid from gthe charge tanks,comprising,` line 140, provided with a ow restricting throat 142,;adapted to admit air or other similar fluid into the systemV at apredetermined pressure toward nozzle 144 and, throughline 146, to flowcontrol valve 148,in line 150. The latter line receives liquid removedfrom either orI both of tanks 66 and 6s. adjacent nozzle 144 and usuallynormal thereto, is a..l apper 154adapted at various times tosubstantiallycover Vand move toward nozzle 144.l Movement of pressure,

indicator 110 is transmitted to apper 154 by a suitable linkage, such asa rigid mechanical linkage 156, which is pivotally attached to bothpressure indicator 110 and flapper 154. Movement of index arm 118 istransmitted to nozzle 144 by a suitable linkage, such as a rigid Vmefchanical linkage 158, which is pivotally attached at one end to theindex arm and the other end to the upper portion of line 146. In orderto permit movement of nozzle Vone end of which'is attached to Alinkagel158, with the'`4 other end thereof inabutting relationship or attachedto a fixed plate-like member 164 disposed about linkage 158. i Flowcontrol valve 148 `is such that the opening `or closing thereof iscontrolled by the air pressure in line 146. Referring to Figure 5, whichillustrates a typical valve which can be employed in the practice of myinvention, valve 148 is a `relay operated pressure controlled valveusing air or other suitable fluid pressure as the amplifying means andcomprises a diaphragm 166 and a plunger or valve stem 168 attachedthereto. Valve .stem 168 is provided with a valve plug 170` at the freeend Y thereof which is adapted to move toward and away from i valve seat172 and permitor restrict the ow of liquid obtaining a readingfthereofon panel 112, othermeans, could. also be used in'V accordance with myinvention to measure. the hydrostatic head of the liquid and irecord;

thesame on panel 112."

Alsopivotally Vmountedlonpanel-112 on a'hollow other fluid under asuitable pressure, say about 3 to about V30 pounds, sufficient to forcevalve plug 170 in closingv engagement with valve seat 172, is introducedin line140.. Since noy air escapes throughnozzle 144, substantially/yallof the air pressure is brought to bear upon diaphragm y 166,.witl1theresult that valve 148k issubstantiallyclosed;

andlittle or no. liquidis permittedto pass therethijtpugllg, l

Pivotally mounted at 152,

assess@ -aving determined beforehand the desired weightof liquid to bedischarged from tank 66 per unit time, and knowing the desired openingnecessary in valve 148 to permit the gravity ow of such liquidtherethrough,'in accordance with the instant embodimentof my inventionthe amount of air or uid pressure necessary to obtain the desiredopening therein is brought to bear. upon diaphragm 166 of valve 148. Inessence, this is accomplished by varying the relative relationshipbetween nozzle 144 and flapper 154 in order to obtainV the desiredpressure in line 146. l

Y In the embodiment shown, cam 132 is rotated at a predetermined speedand in a counter-clockwise direction so that one of fingers 134 contactsshaft 128, which in turn causes roller 126 to move from one end of slot124 to the left toward the other end of the slot. At the same time,shaft 128 of roller 126, lextending through slot 120 of index arm 118,moves the index arm to the left against the action of spring 162,resulting in substantially linear movement of index arm 118 overcalibrations 114. The movement of index arm 118 is transmitted to nozzle144 through linkage 158, whereby the nozzle is moved away from apper154. Since air can now escape from nozzle 144 faster than air can enterthrough ow restricting.

throat 142, the pressure in line 146, and thus on diaphragm 166, isreduced. With less pressure on diaphragm 166, spring 174 is able to movevalve plug 170 partially away from 'valve seat 172, permitting the flowof some liquid through the valve.

As liquid in tank 66 is withdrawn therefrom and the net result is thatpressure indicator 110 willat alltimes` tend to follow and assume thesame initial relative" position as index arm 118. Thus, as index arm 118moves from a high-pressure reading on panel 112 to a low-pressurereading in accordance with movement of cam 132, pressure indicator 110will also move from a high-pressure reading to a low-pressure reading.'Y

As noted, when tank 66 has been discharged of its liquid contents,pressure indicator 110 and index Aarm 118 have moved to the left onpanel 112. Substantially instantaneously upon completion of flow ofliquid from tank 66, index arm 118 makes contact with and actuatesswitch means 136, closing valves 74 and 90 and opening valves 76 and 92.Substantially immediately manometer 78 measures the hydrostatic head ofthe liquid in tank 68 and pressure indicator 110 moves to the right andwith it flapper 154. Cam 132 is so designed in the instant embodimentthat substantially at the moment the switch is made from tank 66 to tank68, the finger 134 which had been in engagement with shaft 128 is freedtherefrom and spring 162 returns the index arm to its initial position.Substantially at the moment index arm `118 and pressure indicator 110have returned to their initial position shown in Figure 3, another oflingers 134 engages shaft 128 and ow of liquid continues this time fromtank 68 in the manner similar to the flow from tank 66 described above.During discharge of liquid from tank 68, tank 66 can be relledand, uponcompletion of flow of liquid from tank 68, index arm 118 again makescontact with switch means 136, as before, this time opening valves 74and 90 and closing Valves 76 and 92. In this way, the flow of liquid ismade substantially continuous. My invention can still be employed incases where the weight rate of flow of liquid need not be continuousvand ple, in the event only the amount of liquid from one tank, say tank66, is necessary in an operation, thus obviating the need for anothertank, upon completion of ow of liquid from tank 66 pressure indicator110 and index arm 118 can be moved to their original position by anyconthrough, and tank 66 is filled with liquid, resulting in movement ofpressure indicator 110 to the right on panelY 112. When low of liquidfrom tankV 66 is again desired, cam 132 is again started and, uponcontinuation ofl rotation, finger 134 leaves the surface'of shaft 128,permitting spring 162 to move index arm 118 to the right. Valve 74 isthen opened by hand and the ow of liquidfrom tank 66 is continued asbefore.

While I have shown a particular cam for moving index arm 118 at apredetermined rate, it is within the scope of my invention to employother means as Well as cam means of other designs for moving the indexarm at a predetermined rate to obtain the desired relative movementbetween nozzle 144 and ilapper 154 and the desired pressure in line 146.Thus, a reciprocating element could be mounted in direct 'contact withindex arm 118'and moved at such a rate as to obtain the desired movementin the index arm. Moreover, index arm 118 audits associated cam 132 andlinkage means could be eliminated in some cases and a reciprocatingelement could be mounted in direct engagement with line 146 aboveflexible joint 160 and moved at such rate to obtain the desiredrelationship between nozzle 144 and fiapper 154.

While the cam `illustrated in the speciic embodiment has been shown asbeing of such design and is said tokbe rotated at such speed to obtain adesired weight rate of flow, it is within the scope of my invention tovary the shape of the cam and its speed to obtain any desired Weightrate of flow of yliquid from the charge tanksV through line 150, Thus,not only can any ,desired'pxed' rate of flow of liquid be obtained bydesigning the'cam to advance index arm 118 at a xed linear rate, butalso any desired variable ilow pattern can be produced. ,For

example, a flow of l0' pounds of liquid per minute for 30 minutes couldbe obtained, the ilow could be stopped v for 5 minutes, after which theoperation could be continued with a flow of 20 pounds per minute for l0minutes. Again, operation could be started with a ow of 5 pounds perminute which could be increased steadily for 3 hours to a iinal rate of25 pounds per minute. The pattern could, if desired, be related to thetank contents. For instance, one-fourth of a tank could be dischargeduniformly in one hour, another fourth uniformly in the next departingfrom the spirit and scope thereof, and therefore only such limitationsshould be imposed as are indicated in the appended claims.

`I claim:

1. A method of'continuously controlling the weight rate of flow ofliquid from at least two receptacles, each containing a selected amountof said liquid, which com-V prises continuously measuring thehydrostatic head of said liquid in one of said receptacles, removingliquid from said onereceptacle and controlling the flow of liquidiv twoor more charge tanks are not necessary. For exam-l fa-,scacco therefromwith a iluid under pressure, continuously varying the pressure of saidfluid in accordance with changes in fsaid hydrostatic pressure,substantially immediately upon completion of ow of liquid from said onerecepu tacle continuously measuring the hydrostatic head of said 5liquid in another of said receptacles, removing liquid from said latterreceptacle and controlling the flow of liquid therefrom with a fluidunder pressure, continuously varying the pressure of said latter uid inaccordance with changes vin said latter hydrostatic head, and continuingl the weight rate of ilow of liquid from a receptacle containing aselected amount of. liquid upon completion'ofv flow of liquid from areceptacle in the manner described above, whereby a continuous operationis obtained.

2..A system for continuously controlling the weightk l rate of flow ofliquid sequentially from at least two recepltacles, which comprises atleast two receptacles, each provided'with a liquid discharge line, meansfor continuously measuring the hydrostatic head of said liquidV inone'of said receptacles, pressure actuated means'for con- 20 trollingtheV rate of flow of 4liquid from each of said receptacles, means forcontinuously varying the pressure on said pressure actuated means inaccordance with changes'v in said hydrostatic head, and means adaptedsubstantially immediately upon completion of ow of liquid -from said onevreceptacle to continuously measure the hydrostatic head in another ofsaid receptacles and permit the flow of liquid from said latterlreceptacle.

3. A system for ,continuously controlling the rate of How of liquid fromat least one receptacle provided withl A Y sponseto changeV inhydrostatic pressure of said liquid Y in'said receptacle, and meanslinking said index arm'and, said pressure indicating arm with said fluidpressure 'vary-V lng means. Y i 4. A system for continuouslyVcontroll'mg the rate ofV 45 ow of liquidfrom at least Vonereceptacle'provided with Y a liquid discharge line, comprising pressureactuated valve means for controlling the rate of flowV of liquid throughsaid dischargeline, meansV for supplying afluid under pressure to saidpressure actuated valve means, movable nozzle means in said iluidsupply" means adapted `to permit escape of fluid from said supply'means,movable means mounted adjacent said nozzle means and adapted uponmovement thereof to follow said nozzle meansand to aid in controllingthe escapeV of saidfluid from said nozzle means, and cam operated meansdirect ly attached to said nozzle means for continuously adjust-YV lng`the relative distance betweenV said nozzle and said movable means,whereby the pressurelon Said pressure actuated valve is continuouslyvaried.

5.` A system for continuously controlling the ratev of. ow of liquidfrom at least one receptacle provided with a liquid discharge line,comprising pressure actuatedvalve meansfor Vcontrolling therate of llowof liquid through` saidvdischarge line, means for supplying a fluidunderV pressure to said pressure actuated valve means, nozzlef means insaid fluid supply means adapted to permit ese,y cape of said fluidtherefrom, movable means mounted ad. jacent said nozzle means andadapted 'uponfmovement thereof to aid in'controlling the escape of saidfluid'ifrom 70 said nozzle means,'a lpivotally mounted index arm,` aro-`tatable cam'mounted adjacent thereto and adapted upon rotation to'movesaid index. arm, and a'pivotally mountedpressure-indicating arm`Yadaptedto movein response to change in hydrostatic pressure of saidliquid in said eating armA and Ysaid pivoted means.

receptacle, said index arm and saidpressureY indicating. arm adapteduponemovement to varytherelative distance between said nozzle'meansand'ksaid movable -means, wherebyv the pressure .on said pressure,-actuatedvalve is continuously varied,Y n

Y6. 'A system for'continuously controlling the rate of flow ofV liquidfrom'rat least one receptacle'provided with a liquid discharge line,comprising pressure actuated valveA said discharge line, means forsupplyinga fluid under' pressure to said pressure actuated valve means,nozzle'V means in said fluid supply'means adapted to permitescape ofsaid fluid therefrom, pivoted meansY mounted adjacent'said nozzle meansand adapted upon movement thereof to aid in controlling theV escape ofsaid lluidfrom' said nozzley means, apivotallymounted index arm, aVrotatable cam mountedV adjacent thereto andada'ptedsupon' A meansforcontrolling vthe rate of flow of liquid through'` rotation to move saidindex arm, `a pivotally mountedv Y pressure indicating arm' adapted tomove 'in response to change in theliydrostaticrpressure of saidliquid insaidY receptacle, means insaid iluid supply Vmeans to permitpivotal'movement of said nozzle means, means linkingl saidindex arm"with said nozzle means, and meanslinking said pressure `indicating annand said pivoted means,A

25 wherebywthepressure on said pressure actuated valve is continuouslyvaried.

f 7. AV .system for continuously controlling .the rate ofY flow ofliquid from at least one receptacle provided Witha Aliquid dischargeline, comprising pressure actuated valve .means'for controlling thefrateof Vflow of liquid through said discharge line, means for supplying afluid under ypressure to said pressure actuated valve means,Y

nozzle means" in said uid supply means adapted to permit escape ofsaid-uid therefrom, pivoted means mounted adjacent said Vnozzle meansand adapted uponV movementthereofto. aid in controlling the escape oflluid from said vnozzle means, a pivotally mounted index arm,l

a rotatable cam mounted adjacent thereto and adapted upon rotation tomovev saidrindex arm, a pivotally mounted 4pressure indicating arm,manometermeans kfor meas-y uring the hydrostatic head of said liquid'insaid .receptacle and I causing movement of saidpressure`r indicating armupon change of said hydrostatic head, flexible Vmeans in saidfluidpsupply means to permit. pivotal movement ofsaid nozzle means,mechanicalmeans pivotally mounted toeach of saidv index arrn'andsaidpnozzlemeans, andy mechanical means pivotally mountedY toeachek ofsaid pressure indicating arm and said pivoted means, whereby ouslyvaried.

vthe pressure on said pressure actuated valve isf continu-H 8. 'Acontrol device comprising means vfor supplyinga uid under pressure,movable nozzle means in said uid supply means adapted to permit escapeof Huid from said supply means, movable-means mounted adjacent saidnozzle means and adapted upon movement thereof to follow said nozzlemeans and to aid in controlling the escape of said fluid fromsaid`nozzle means, and camoper'ated means directly attachedto saidnozzle means for continuously Vadjusting the relative distance Vbetweensaid Vnozzle and said' movable means.

9. A control device comprising means for supplying a fluidunderpressure, nozzle means in said fluid supply" means adapted to permitescape of saidV fluid therefrom,

pivotedpmeans'mounted adjacent saidno'zzle' means andV adaptedupoumovement thereof to aid incontrollingtheVV theretoand adaptedupon'rotationV tofmove saidindexy nozzle -means,and means llinking saidpressure` indi- 10. A control device comprising means for supplying vescape of said fluid from said nozzle means,a pivotally mountedy indexarm, aqrotatable'c'arnV mounted adjacentV fluid under pressure, nozzlemeans in said fluid supply means adapted to permit escape of said fluidtherefrom, pivoted means mounted adjacent said nozzle means and adaptedupon movement thereof to aid in controlling the escape of uid from saidnozzle means, a pivotally mounted index arm, a rotatable cam mountedadjacent thereto and adapted upon rotation to move said indexv arm, apivotally mounted pressure indicating arm, manometer means for measuringthe hydrostatic head of 1iq uid in a receptacle and causing movement ofsaid pressure 10 each of said pressure indicating arm and said pivotedmeans.

References Cted in the le of this patent UNITED STATES PATENTS 1,370,641Grant Mar. 8, 1921 1,826,112 Wilson Oct. 6, 1931 2,258,360 Helzer Oct.7, 1941 2,314,899 Samiran Mar. 30, 1943 2,418,858 Urquhart Apr. 15, 19472,504,304 Cowan Apr. 18, 1950 2,509,629 De Giers et al. May 30, 19502,517,718 Sall Aug. 8, 1950

